Electrically conductive tape device

ABSTRACT

An economical, disposable, flexible, slip or skid resistant, electrically conductive strip device is formed which is useful for temporary attachment to shoes, booties, or the like to provide for the dissipation of static electricity from the bodies of personnel in environments containing explosive or inflammable materials. The strip device comprises a flexible, skid resistant, conductive strip having at one end a footwear-sole-engaging portion provided with pressure sensitive adhesive for attachment to the personnel&#39;&#39;s footwear and means at the other end for temporary electrically conductive attachment to the body of the personnel.

United States Patent [191 Oehmke et al.

[ ELECTRICALLY CONDUCTIVE TAPE DEVICE [75] Inventors: Richard W. Oehmke,Hudson Twsp., St. Croix Cty., Wis.; Paul H. Schertler, St. Paul, Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul,Minn.

[22] Filed: Oct. 2, 1972 [21] Appl. No.: 294,075

[52] U.S. Cl. 317/2 B, 174/117 A [51] Int. Cl. A61n 1/14, HOlb 7/08 [58]Field of Search 317/2 R, 2 B; 174/117 A [56] References Cited UNITEDSTATES PATENTS 2,785,344 3/1957 Hines I 317/2 B 2,955,234 10/1960 Price317/2 B Wilhelm 174/117 A 1 1 Aug. 27, 1974 3,132,204 5/1964 Giellerup174/117 A 3,358,188 12/1967 Zimmon 317/2 B 3,505,144 4/1970 Kilduff eta1 174/1 17 A Primary ExaminerL. T. I-Iix Attorney, Agent, orFirmAlexander, Sell, Steldt & DeLahunt ABSTRACT An economical,disposable, flexible, slip or skid resistant, electrically conductivestrip device is formed which is useful for temporary attachment toshoes, booties, or the like to provide for the dissipation of staticelectricity from the bodies of personnel in environments containingexplosive or inflammable materials. The strip device comprises aflexible, skid resistant, conductive strip having at one end afootwearsole-engaging portion provided with pressure sensitive adhesivefor attachment to the personnels footwear and means at the other end fortemporary electrically conductive attachment to the body of thepersonnel.

' 8 Claims, 4 Drawing Figures ELECTRICALLY CONDUCTIVE TAPE DEVICEBACKGROUND OF THE INVENTION In one aspect this invention relates toflexible electrically conductive strip devices. In yet another aspect,this invention relates to shoes suitable for dissipating staticelectricity from the body of personnel.

It is common practice in many areas where there are stored flammable orexplosive liquids or dust which could be ignited by an electric spark toprovide some means of dissipating static electricity before it canaccumulate to the point where an electric spark could form. Whenpersonnel are working in the area generally the static charges aredissipated by providing an electrically conductive path from the body ofthe personnel to the ground. The ground can be any electricallyconductive mass of material such as a metal pipe which is in intimatecontact with the earth and will provide a means of dissipating thestatic charge.

To dissipate static charges that may accumulate on the body of personnelin solvent storage areas, hospital operating rooms, flour mills, and thelike where electrical discharge is a great hazard, the workers useslippers, overshoes, gloves, disposable booties and other clothing whichis electrically conductive and has one end of a flexible conductivestrap attached to the clothing by stitching, solvent adhesives, or othermeans of making a coherent electrical contact. The other end of theelectrically conductive strap is wrapped about the ankles, tucked intothe socks, or otherwise attached to the personnel to provide aconductive path from the body of the personnel to the ground.

Presently available devices are exemplified by foot coverings such asthose disclosed in U.S. Pat. Nos. 3,281,624 and 3,605,291, wherein anelectrically conductive strip is attached to a disposable foot coveringhaving an electrically conductive sole. The attached strip is wrappedabout the ankle or tucked into the socks of the wearer thereby formingan electrically conductive path from the body of the wearer to thesurface on which he is standing.

Although the disposable shoes and the like described hereinabove fordissipating static electricity from the body of personnel in hazardousareas are satisfactory from safety point of view, they are expensive inthat they constitute a special shoe or shoe covering which is of useonly in certain areas. Also the prior art devices are special serviceitems which have only limited utility despite their high cost.

SUMMARY OF THE INVENTION It has been found that the electricallyconductive strip made in accordance with this invention provides aconveniently used, easily applied, disposable means for adapting shoes,slippers, overshoes, booties and the like into skid resistant,electrically conductive grounded clothing. The strip of this inventionis a flexible, disposable, electrically conductive strip comprising aelongated flexible, skid resistant, electrically conductive materialhaving a footwear-sole-engaging portion at one end thereof provided witha pressure sensitive adhesive over at least a portion thereof and a bodycontacting portion distally to said footwear engaging portion adaptedfor temporary attachment to the leg adjacent to said footwear inelectrical contact with the skin of the wearer and in non-interferingrelationship as re gards locomotion.

BRIEF DESCRIPTION OF THE DRAWING A further understanding of theinvention can be had by referring to the accompanying drawing in whichlike reference numbers refer to like parts in the several views and inwhich:

FIG. 1 is'a side view in section of one embodiment of the flexibleconductive strip of this invention;

FIG. 2 is a side view in section of another embodiment of this inventionhaving an electrically conductive adhesive on one end thereof;

FIG. 3 is a side view in elevation illustrating the strip device of FIG.2 attached to a shoe; and

FIG. 4 is a perspective view of a jumbo roll of mate rial suitable forbeing converted to the strips of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS tive strip to the sole of ashoe or other piece of apparel which is to be grounded. Pressure,sensitive adhesive 12 is protected by a release liner 13 which may be apiece of silicone-treated paper or other similar release liner known inthe art for protecting adhesives. When the electrically conductive strip10 is attached to a shoe or other apparel desired to be grounded, thedistally opposed free end 14 of the strip can be wrapped about the bodyof the wearer in contact with the skin or tucked into a sock or wristletin contact with the skin of the wearer.

Another embodiment of the invention, as shown in FIG. 2, has a strip ofconductive material 11 having on one end thereof a pressure sensitiveadhesive 12 covered by release liner 13 similar to the configurationshown in FIG. 1. The electrical strip device 16 has on the opposite endof conductive material 11 a coating of pressure sensitive adhesive 17,covered by release liner 18, which is electrically conductive, adhesive17 covering the width of the material for about 2 to 5 centimeters.Adhesive 17 being conductive provides a means for attaching theconductive strip to the body of the wearer providing a firm,electrically conductive connection between the body of the wearer andthe flexible conductive strip 11. When the electrically conductivedevice of this invention 16 is to be used, the release liners l3, 18 areremoved and the pressure sensitive adhesive 12 applied to the sole of ashoe 19 or other footwear as shown in FIG. 3. The resultingconfiguration has a substantial portion of the electrically conductive vstrip 11 in contact with the ground, forming grounding means, and theremainder of the strip can be brought into electrical contact with theankle 21 by means of the pressure-sensitive adhesive 17.

It is also convenient to produce a jumbo roll of conductive materialsuitable for producing numerous strips as shown in FIG. 4. Theconductive material 11 is produced in the form of an elongated sheetwhich has a pressure-sensitive adhesive 12 and a release liner 13 alongone edge of the elongated sheet. The embodiment in FlG. 4 has a strip ofconductive adhesive 17 protected by a release liner 18. When strips arecut from the jumbo roll 22 across the width as shown by the dotted lines23 the resulting strips will be similar in configuration to FIG. 2. Ofcourse the conductive adhesive could be omitted and a conductive stripsimilar to FIG. 1 formed.

The flexible, electrically conductive material useful in the stripdevice of this invention may be prepared from numerous flexible,electrically conductive compositions. Suitable conductive compositionsinclude rubbery polymeric materials containing an electricallyconductive powder that can be blended to a uniform compositionandextruded, calendered or otherwise formed into sheets of a thicknessof about 0. 1-1 .25 millimeters. Optionally, the polymeric compositionmay be impregnated, such as by pressure lamination to a textile fabric,to provide greater dimensional stability to the sheeted composition.

Suitable polymeric materials for use in the electrically conductivestrip of this invention include natural and reclaimed rubber, butylrubber, polyisoprene, cisbutadiene, styrene-butadiene rubbers,ethylenepropylene-polyene terpolymer rubbers commonly known as EPDM"rubbers, polymers and copolymers of chloroprene, polyacrylates,polyvinyl alkyl ethers, and the like. The elastomeric polyurethanes andpolyureas provide still other known elastomers that are useful in thepractice of this invention. The preferred source of polymeric materialfor use in the flexible electrically conductive strip of this inventionis scrap and recovered vulcanized elastomeric material resulting fromthe molding and forming of automobile tire products. Particularlypreferred is the rubber scrap generated during the skiving andretreading of automobile tires. For use, the vulcanized scrap andrecovered elastomeric materi' als are comminuted by cutting or grinding,blended with a thermoplastic binder containing an electricallyconductive powder and formed into sheets by calendering or other meansknown in the art.

Suitable thermoplastic binders which may be used in the practice of thisinvention include the natural and synthetic elastomers capable of beingvulcanized that are mentioned hereinbefore and thermoplastic polymerssuch as polyvinyl halides, e.g. polyvinyl chloride and plasticizedpolyvinyl chloride; copolymers of vinly chloride and vinly acetate;vinylidene chloride polymers and copolymers of vinyl chloride, vinylacetate, acrylonitrile; styrene polymers and copolymers as for example,styrene copolymers with ethylene, butylene, butadiene, methylacrylate,and the like; polyolefins, e.g., polyethylene and polypropylene; andhalogenated polyolefins, e.g. chlorinated polyethylene. Preferredbinders are the copolymers of ethylene and copolymerizable olefinicallyunsaturated monomers such as described in U.S. Pat. No. 3,489,710 andthe ABA block polymers such as described in U.S. Pat. No. 3,231,635.

The amount of particulate elastomer used in the conductive compositionof this invention can vary from about 0.5-9 parts by weight of elastomerper part of thermoplastic binder with a preferred composition beingabout 3 to 6 parts by weight of particulate elastomer per part ofthermoplastic binder.

Suitable electrically conductive powder for use in the flexibleelectrically conductive material includes finely divided electricallyconductive metals, e.g., silver, gold, aluminum, copper or zinc andconductive forms of carbon, e.g. graphite and gamma-carbon black. Theaverage particle size of the conductive powder and the amount used inthe conductive material will vary with the conductive material used. Forexample, where nickel particles are used it is preferred that theconductive powder have an average particle size of about 2-4 microns andthat the nickel particles be present in the composition from about 1 to25 percent by volume. Where a conductive carbon black is used, it ispreferred that the average particle size be from 2080 millimicrons andbe present in amounts from about 1 to 50 percent by volume. Anotheruseful conductive powder is a silver-coated ceramic particle availableas Sil- Clad-Microspheres" (a registered trademark of SigmatronicsCompany). When such coated particles are used, it is preferred that theaverage particle size be of about 5-40 microns and be present in thecomposition from about 560 percent by volume. In addition to theconductive powder or coated microspheres, the conductive composition maycontain additives such as fillers, e.g. silica, clay, talc;antioxidants; vulcanizing agents, e.g. sulfur, peroxides; dyes;pigments, e.g. zinc oxide, titanium oxide; plasticizers and lubricants.

The pressure sensitive adhesive suitable for use for attaching theconductive tape device of this invention to shoes or other articles ofclothing may be any pressure sensitive adhesive having a peel adhesionof at least 0.14 kilograms pre centimeter width as determined by ASTMDl000-6 1. Examples of suitable pressure sensitive adhesives includeadhesives composed of rubbery polymeric material such as those polymericmaterials mentioned hereinbefore for use in the electrically conductivecomposition. The polymeric materials are modified according to theprocedures well known in the adhesive art by the addition ofplasticizers, tackifiers, fillers, solvents and stabilizers. Preferredpressure sensitive adhesives are the copolymers of alkyl acrylates andacrylic or methacrylic acid, the copolymers of alkylacrylates and maleicanhydride and the copolymers of alkyl acrylates and acrylimide. Of thesecopolymers the most preferred pressure sensitive adhesive is thecopolymer of isooctylacrylate and acrylic acid because of itsavailability and ease of handling.

The electrically conductive pressure-sensitive adhesive useful in oneembodiment of this invention may be formed from the pressure sensitiveadhesives hereinbefore mentioned to which has been added one of theaforementioned conductive powders. The presently preferred electricallyconductive pressure sensitive adhesive is a composition composed of asoft, highly conformable adhesive, a plurality of insoluble softspherical domains, and a conductive powder such as those described incopending patent application Serial No. l73,857 filed Aug. 23, i971.

The electrically conductive strip of this invention can be manufacturedby blending the desired rubbery polymeric material, conductive powderand additives on a rubber mill to form a flexible electricallyconductive composition. Generally, mixing times from about 3 to 30minutes or longer are sufficient to thoroughly mix the ingredients withthe shorter times being preferred since electrical resistivity increasesafter optimum mixing with increased mixing times. The resultingcomposition is then calendered, extruded or otherwise molded to form asheet of flexible electrically conductive material having a thickness ofabout 0.1 to 1.25 millimeters which can be cut into widths of 30 to 75centimeters and wound onto a large roll. Where particulate elastomericmaterial such as reclaimed rubber particles is used it is alsoconvenient to blend the particulate elastic material, the binder,conductive powder and additives and then to mold the composition into abun or other configuration followed by skiving the resulting mass intosheets of flexible conductive material which can be wound into rolls.

A pressure-sensitive adhesive is applied to the sheet of flexibleconductive material by techniques known in the art, such assolvent-casting the pressure-sensitive adhesive along a portion of oneside of the sheet material. When solvent-casting of this adhesive isused, the solvent is removed and a strip of release liner applied overthe pressure-sensitive adhesive to protect the adhesive, and the sheetmaterial may be rewound for convenient storage. Alternatively thepressure-sensitive'adhesive can be applied by laminating a transferadhesive and release liner to a portion of one side of the conductivesheet material.

If desired, an electrically conductive pressure sensitive adhesive canbe applied to the other side of the sheet material in a manner similarto and simultaneously with the pressure sensitive adhesive designed toattach the electrically conductive strip to the shoes of the personnelto be protected.

The flexible conductive strip devices can be obtained from the sheet ofmaterial by use of a guillotine cutter or similar device forcuttingstrips perpendicular to the width of a large sheet of material or rollof material which is being unwound. For use in making a large quantityof strips or booties having strips attached, the conductive material isformed into a long sheet and pressure-sensitive adhesive is appliedalong one edge. The material can then be cut into strips having apressure-sensitive adhesive on a portion of the strip suitable forattaching to a shoe or the like.

Further understanding may be had by reference to the followingnonlimiting examples in which all parts are by weight unless otherwisespecified.

EXAMPLE 1 A thermoplastic binder was formed by mixing parts ofstyrene-butadiene-styrene. block copolymer wherein the styrene blockshave a molecular weight of about 14,000 and the butadiene block has amolecular weight of about 80,000 on a rubber mill at l25-l 50C. forabout 20 minutes. Fifteen parts of ground rubber particles, (obtainedfrom an automobile tire recap operation), having a particle size suchthat substantially all the pieces passed through a US. Sieve No. 30 wasblended into the thermoplastic mixture for 20 minutes. The compositionwas sheeted from the mill and pressed at 150C. in a hydraulic presshaving heated platens to form a sheet 0.75 mm. thick.

The surface resistance of the resulting sheet when measured by a Simpsonvolt-ohm meter with razor blade electrodes was 4,000-7,000 ohms persquare. Physical properties of the material were an ultimate tensilestrength of 665 pounds per square inch and an elongation at break of 290percent.

The flexible electrically conductive sheet material was cut into strips1.5 cm. in width by 60 cm. in length and one end of the strips was knifecoated on one side with a thin layer of an acrylic pressure sensitiveadhesive comprising a 20 percent solution of a isooctylacrylate: 5acrylic acid copolymer in isopropanol and heptane for a distance ofabout 5 cm. and the adhesive allowed to dry. The adhesive was protectedby covering with a piece of silicone treated release liner to provide aconductive tape device similar to the configuration shown in FIG. 1.

The conductive strip device of this invention could be readily attachedto footwear such as shoes, slippers, paper booties and the like byremoving the release liner and attaching the conductive strip to thesole of the footwear by means of the adhesive. When such footwear wasworn by personnel and the unattached end of the strip tied around theankle of the personnel, static electrical charges did not accumulate onthe body of the personnel wearing the altered footwear but weredissipated from the body of the person to the ground.

EXAMPLE 2 The flexible, electrically conductive composition of Example 1was mixed in a Banbury mixer until the temperature had risen to C. andthen formed into a 1 millimeter thick sheet on a calendering machine.The composition as formed had a surface resistivity of about 1,000,000ohms per square. Strip devices were formed as in Example 1 from thesheet material of this example and when attached to footwear as inExample 1 dissipated the static electricity from the body of personnelwearing such altered footwear and prevented the buildup of staticcharges on the body of personnel so protected.

EXAMPLE 3 A thermoplastic binder was formed from 8 parts ofstyrene-butadiene-styrene block copolymer such as used in Example 1,24.5 parts of mineral oil and 8.2 grams of conductive carbonbalckcommercially available from Cabot Co. under the tradename XC-72Rmixed on a rubber mill at l25l50C. for 20 minutes. To thethermoplastic mixture 59.4 parts of ground tire rubber scrap such asthat used in Example 1 was mixed and the mixture mixed for 10 minutes.The mixture was sheeted off the mill and pressed between steel plates at150C. to form a sheet having a thickness of 0.5 mm. Surface resistanceof the material was ohms per square. The ultimate'tensile strength ofthe resulting material was 195 psi and the elongation at break was 100percent.

The sheet material was cut into strips 1 cm. wide and 35 cm. long. Onone end of each strip a thin layer of To use the strip device of thisinvention the release I liners were removed from the pressure sensitiveareas and the end of the strip device having the nonconductive adhesivewas applied to the sole of the footwear of personnel and the conductiveadhesive was applied to the ankle. When used in this manner, electricalcharges did not accumulate on the bodies of personnel but weredissipated from the body of the persons wearing such conductive strips.

EXAMPLE 4 The flexible electrically conductive composition of Example 1was compression molded using a hydraulic press having heated platens toform a block of material 60 cm. long by 30 cm. wide by 0.3 mm. thick.Pressure sensitive adhesive was applied to a cm. wide strip along oneedge as in Example 1 and a release liner used to cover the adhesive. Thesheets were then cut into strip devices 60 cm. long by 2 cm. wide andwere useful for dissipation of static electricity when tested using theprocedure of Example 1.

EXAMPLE 5 A flexible electrically conductive composition was prepared bymixing on a rubber mill 9 parts of smoked natural rubber, 1 part ofpolybutene oil, and 10 parts of ground tire scrap. After mixing for 30minutes, 3.5 parts of conductive carbon black was milled in and thematerial sheeted from the mill and pressed between two steel plates at150C. to form a sheet 1.0 mm. thick. Surface resistivity, measured as inExample 1, was 5,500-7,500 ohms per square. The ultimate tensilestrength was 690 psi, the elongation at break was 225 percent. Theconductive sheet composition was cut into strips 30 cm. long by 2 cm.wide and pressure sensitive adhesive applied as in Example 2. Theresulting conductive tape was effective to prevent the accumulation ofstatic electricity on the body of personnel wearing such a stripattached to the ankle and to their footwear.

EXAMPLE 6 A flexible electrically conductive composition was prepared bymixing on a rubber mill 10 parts of an ethylene-ethylacrylate copolymercontaining about to percent ethylacrylate, 2 grams of dibutylphthalateand 3.5 parts of conductive carbon black. After mixing for about 15minutes, 30 grams of finely shredded rubber tire scrap was milled intothe mixture and the material sheeted from the mill and pressed betweentwo steel plates at 300C. to form a sheet 1 mm. thick. The surfaceresistivity of the conductive sheet as measured in Example 1 was 500ohms per square. The ultimate tensile strength was 500 psi andelongation at break was 50 percent. Conductive strip devices prepared asdescribed in Example 2 were readily attached to footwear and allowed forthe dissipation of static electricity from the body of personnel wearingthe adapted footwear.

EXAMPLE 7 A flexible electrically conductive composition was prepared bymixing on a rubber mill 20 grams of smoked natural rubber, 1.6 grams ofcoal tar oil, 1 gram zinc oxide, 0.6 grams stearic acid, 0.1 gram ofbenzothiazyl disulfide and 0.5 grams of sulfur. After mixing for 10minutes, 6 grams of conductive carbon black were mixed in and thematerial sheeted from the mill and pressed between two steel plates at145C. to form and cure a conductive sheet 1.0 mm. thick. Surfaceresistivity measured as in Example 1 was 60-150 ohms per square, and theresulting material had a tensile strength of 3200 psi and an elongationat break of mer, (Kraton" 1107), 4 parts of mineral oil, 45 parts 600percent. Conductive strip devices prepared as described in Example 2were readily attached to footwear and allowed for the dissipation ofstatic electricity from the body of personnel wearing the adaptedfootwear.

EXAMPLE 8 The procedure of Example 7 was repeated usingstyrene-butadiene rubber (SBR-1500 available from Imperial ChemicalIndustries) in place of the smoked natural rubber. The flexible,electrically conductive sheet material had a surface resistivity of 700to 2100 ohms per square, a tensile strength of 2660 psi and anelongation at break of 750 percent. Conductive strip devices prepared asdescribed in Example 2 were readily attached to footwear and allowed fordissipation of static electricity from the body of personnel wearing theso adapted footwear.

EXAMPLE 9 Six parts of styrene-isoprene-styrene block copolyof nickeldust (having particle size of about 3 microns), and 4 parts of groundwhite wall rubber scrap (particle size less than 1 millimeter) wereblended together on a rubber mill at 250F. The components were blendedin sequence the total milling taking minutes.

The resulting mixture was formed into a 1.25 millimeter thich sheet bypressing between two sheets of silicone treated release paper.

The physical properties of the conductive material were resistivityabout 2.5 l0 ohms per square, tensile strength 9.8 kilograms per squarecentimeter and elon gation at break percent. The conductive materialproduced was suitable for forming conductive strips.

EXAMPLE 10 The milling procedure of Example 9 was repeated substituting30 parts of silver coated ceramic beads (available as Sil-Clad-Gl00,from Sigmatronics Laboratories Inc.). 1

The milled mixture was warm pressed to 0.75 millimeter thick betweenheated platens at 250F. and 1000 pounds per square inch.

The resistivity was about l-2 ohm per square. The tensile strength was3.2 kilograms per square centimeter, and the elongation at break waspercent.

It is possible to use a variety of conductive particles to form theconductive material useful in the practice of this invention.

What is claimed is:

1. A flexible, one-piece elastomeric skid resistant, disposableconductive strip for one-time use for electrically grounding the humanbody, comprising an elongated strip of flexible, electrically conductiveelastomeric material having a foot wear-sole-engaging portion at one endthereof provided with pressure-sensitive adhesive having a peel adhesionof at least 0.14 kilograms per centimeter of width over at least aportion thereof and a body-contacting portion distally to saidfoot-engaging portion adapted for temporary attachment to the legadjacent to said foot wear in electrical contact with the skin and innoninterfering relationship as regards locomotion.

2. The conductive strip of claim 1 having a conductivepressure-sensitive adhesive on the end distal to the pressure-sensitiveadhesive on the footwear-soleengaging portion.

of pressure-sensitive adhesive, and a release liner surfacing saidpressure-sensitive adhesive.

7. The material of claim 6 having in addition an electrically-conductivepressure-sensitive adhesive protected by a release liner on a portion ofthe sheet distal to the pressure-sensitive adhesive.

8. The material of claim 7 where said conductive sheetcomprises anelastomer, a thermoplastic binder,

and a particulate conductive material.

1. A Flexible, one-piece elastomeric skid resistant, disposableconductive strip for one-time use for electrically grounding the humanbody, comprising an elongated strip of flexible, electrically conductiveelastomeric material having a foot wearsole-engaging portion at one endthereof provided with pressuresensitive adhesive having a peel adhesionof at least 0.14 kilograms per centimeter of width over at least aportion thereof and a body-contacting portion distally to saidfoot-engaging portion adapted for temporary attachment to the legadjacent to said foot wear in electrical contact with the skin and innoninterfering relationship as regards locomotion.
 2. The conductivestrip of claim 1 having a conductive pressure-sensitive adhesive on theend distal to the pressure-sensitive adhesive on thefootwear-sole-engaging portion.
 3. The conductive strip of claim 1 wheresaid conductive strip comprises an elastomer, a thermoplastic binder,and particulate conductive material.
 4. The conductive strip of claim 3where said particulate material is carbon black.
 5. The conductive stripof claim 3 where said elastomeric material is rubber.
 6. A convolutelywound roll of material suitable for being cut into flexible, elongated,conductive strips comprising a sheet of flexible elastomeric,electrically-conductive material having on a portion thereof a strip ofpressure-sensitive adhesive, and a release liner surfacing saidpressure-sensitive adhesive.
 7. The material of claim 6 having inaddition an electrically-conductive pressure-sensitive adhesiveprotected by a release liner on a portion of the sheet distal to thepressure-sensitive adhesive.
 8. The material of claim 7 where saidconductive sheet comprises an elastomer, a thermoplastic binder, and aparticulate conductive material.